The ‘Business as Usual’ scenario is the average building the industry would build in the absence of a more economical alternative and with the continued lapse in enforcement of codes related to energy efficiency where they exist—such as in Ontario. In general, these buildings just barely meet the most basic requirements of the Ontario Building Code (OBC), and in some cases directly oppose the code. All heating, cooling and ventilation is provided through standard efficiency packaged constant volume rooftop units sized at 200 ft²/ton. Meanwhile the ventilation is sized to 20% of the supply flow, which requires significant conditioning for outdoor air and typically over ventilates in all but the most extreme of occupant densities. Envelope constructions frequently do not take into consideration the effects of thermal bridging, and rarely include upgrades to performance. Retail lighting is often significantly over the ASHRAE 90.1(2007 allowances (OBC), and the controls for lighting usually include a manual switch—frequently not turned off at night. These
characteristics are summarized with a prescriptive target in the table below.
Table 3: Business as Usual Prescriptive Summary
Assuming an average utility rate of $0.10/kWh for electricity, $0.25/m³ for natural gas, and $0.004/ekWh incremental charge for purchased offset, the estimated utility costs for the ‘Business as Usual’ building are summarized along with the economics of including PV in the following table.
Table 4: Business as Usual Cost Summary
To ensure that 51% of the site energy use is covered by onsite generation, the ‘Business as Usual’ case will require 14.9 kW of roof mounted PV with 116.1 kW of parking lot mounted PV (9 units at 12.9 kW each). The area required for the ground mounted PV will take up approximately 72 parking spaces. Luckily there are several companies that produce racking for use in parking lots that allow cars to park under the PV. An estimation of the required layout is presented below.
Figure 4: Business as Usual PV Array – Significant site area is required